Electromagnets hold the rotor in a levitated position. They generate the bearing forces in active magnetic bearing systems. The rotor position is monitored constantly by a set of sensors which transmit signals to a digital controller at a rate of up to 10'000 cycles per second.
The controller then measures any possible deviation of the rotor from its nominal position and supplies the current signal required to maintain rotor stability. A power amplifier finally transforms this signal into an electrical current for the magnetic bearing coils.